CDMA (Code Division Multiple Access, referred as CDMA) technique is a common multiple modulation technique based on wideband spread spectrum technology. CDMA 2000 1X system conforms to IS-2000 standard, which is in the first phase for the development of CDMA 2000 celluar mobile communication, and can provide transmission rate of 153.6 Kbps for packet data.
FIG. 1 is the network schematic view for the combination of CDMA 2000 1X system and wireless local area network, in which outside the block with dashed lines are function nodes of current CDMA 2000 1X system, and inside the block with dashed lines are function nodes added after a combination of CDMA 2000 1X system and wireless local area network. In the current CDMA 2000 1X system, base station transceivers 11 establish radio coverage area in an area to perform communication of mobile stations; base station controller 12 can control each base station transceiver; a packet control function node PCF generally is comprised in the base station controller 12, which is used for forwarding message between wireless subsystem and packet data service node PDSN 14; the packet control function node PCF connects to base station controller 12 via A8/A9 interface. Packet data service node PDSN 14 is an interface for CDMA 2000 1X system to access Internet, and an interface between packet data service node PDSN 14 and packet control function node PCF 12 is a standard R-P (Radio-Packet) interface, that is A10/A11 interface, in which A10 is data channel, and A11 is control channel. Packet data service node PDSN 14 provides access service for users of CDMA 2000 1X, and users perform authentication and accounting to the Visited Authentication Authorization Accounting server 19, Broker Authentication Authorization Accounting server 17 and Home Authentication Authorization Accounting server 18 via PDSN 14.
When a user requests packet data service, firstly, it goes through mobile switching center 13 to home location register HLR 20 where its validity is authenticated; after the validity is authenticated successfully, A8/A9 interface is established between base station controller BSC 12 and PCF 12, thereafter, PCF 12 transmits message to PDSN 14, and R-P interface is established between PCF 12 and PDSN 14. Then, PPP connection is established between mobile station and PDSN 14. After PPP connection is established successfully, if the user is a simple IP user, data service can start. If the user is a mobile IP user, MIP registration needs further perform, and, after MIP registration is completed successfully, the data service for mobile IP starts. When the user accesses, it needs to perform a full PPP negotiation flow with PDSN 14, in which PPP uses frame-making form of asynchronous HDLC.
Wireless local area network is the result of the combination for computer network and wireless communication technology, which supports communication between computers by using radio multiple access channel, and can provide the data transmission rate of up to 54 Mbps. Terminals of wireless local area network generally dial by using point to point protocol over Ethernet (referred as PPPoE) or web+DHCP (Dynamic Host Configuration Protocol).
Compared to wire network, wireless local area network WLAN has advantages of convenient installation, flexible usage, economy, and easy update, and, therefore, WLAN is used rapidly in the situation where internetworking in mobile and roaming between networks are needed, especially adapts to the situation where line distribution is not easy or data process is performed remotely; particularly in some fields, such as exhibition, meeting, tour service, financial service and mobile office system, WLAN has very great chance for development. The character of wireless local area network is low price, flexible networking, convenient installation, and supporting wireless data access with high speed, which adapts to the application in hot pots such as airport, hotel, etc.
In wireless local area network, wireless terminal accesses fixed telecommunication network via access point AP; AP provides user with the function of wireless access, provides access services of voice and data, and finishes the transfer of 802.11 and 802.3 protocol, in which the data package after converted by AP is Ethernet data package. But wireless local area network has limitation in authentication and accounting mechanism for terminal access, it can only provide authentication on physical transfer layer, but not provide accounting mechanism corresponding to terminal user, therefore, it can not meet the need for applying on telecommunication level, and, moreover, the coverage area of wireless local area network only limits to hot pot areas, which results in very big limitation to the broad application of wireless local area network.
After about 20 years development of CDMA system, CDMA 2000 1X system has recently also been used commercially in big scale. Not only its authentication and accounting mechanism is developed maturely and well, but also its coverage area is universally. But due to the wideband limitation, the capability of CDMA 2000 1X system to provide terminal user with high-speed access service is still limited now. Therefore, if CDMA 2000 1X system and Wireless local area network system are combined to an organic whole, they can exert their respective advantages fully, while the critical problem to combine two systems is how to realize seamless handoff between two systems for terminal users. At present, no technical document has been seen about handoff between two systems for terminal users.